I wouldn't say that this is confirmation, but rather a pretty good sign in favor of Pokémon Stars existing. We won't know for sure until it gets revealed (if it's even real in the first place), likely before the end of May.So this basically confirms the rumor that Pokemon Switch is happening right.
Please be true.
That said, I do hope that Eurogamer's right. Announcing Stars soon after the positive buzz surrounding Mario Kart 8 Deluxe would be a great way to keep the hype train for the Switch going before we get to E3.